Learn the basics about water pollution, whilst learning about environmental chemistry.

The substances mankind throws away have polluted lakes, rivers and even the oceans.

The United Nations estimate that around 10% of the world’s people do not have access to clean drinking water. The main problem with this untreated water is that it can carry diseases, such as cholera, that spread through untreated human faeces. This is particularly serious in shanty towns near big cities and in refugee camps.

Rivers and streams can also be polluted with diseases from water coming from badly managed rubbish dumps. But human sewage is not the only substance that pollutes our water supplies – most of the other substances humans allow to escape into streams, rivers and the oceans, are more a danger to natural ecosystems than to us directly.

Chemical fertilisers are much more soluble in water than organic, manure-based fertilisers, so heavy rain can wash them into streams and lakes, causing eutrophication. The fertilisers cause algae to grow very fast forming a mat on the lake surface, which blocks sunlight from the vegetation deeper down, which then dies. Bacteria feed off the dying vegetation and use up the remaining oxygen supply. Once the oxygen has gone all animal life dies and the lake ecosystem is destroyed.

If heavy metals, such as lead mercury and cadmium, get into rivers and lakes many animals will die.

Radioactive waste is normally stored above ground in water tanks, waiting for a more permanent underground storage where it has to be safe for millions of years. There are fears that these underground stores could fail and contaminate water courses. Following a nuclear disaster, water courses and the oceans can become dangerously polluted with radioactive waste.

During mining and drilling operations to extract minerals from the earth, aquifers, which are underground water courses, can become polluted. Huge amounts of plastic thrown away from ships, and washed out to sea from rubbish dumps on land, have ended up floating in huge islands of waste causing a serious threat to fish, seabirds and other marine animals.

Coal and oil fuelled power stations have been responsible, more so in the past, for causing acid rain.

Fossil fuel and nuclear power stations need large amounts of water for condensing the steam which drives their turbines. This water is usually cooled on site in the great cooling towers that dominate the skyline of power-stations. Even so the water will be returned to the river or sea warmer than before. This can upset the river or sea ecosystems. Although not material pollution this waste heat is a pollutant.

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This video is part of 'Chemistry for All' - a Chemistry Education project by our Charity Fuse Foundation - the organisation behind The Fuse School. These videos can be used in a flipped classroom model or as a revision aid. Find our other Chemistry videos here:

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